Biology (Raven), 9th Edition

Chapter 6: Energy and Metabolism

Post-Test

1
In a chemical reaction, if the reactants have less free energy than the products,
A)The reaction will tend to be spontaneous.
B)The reaction will give off energy.
C)There is no need for activation energy.
D)Catalysts will not affect the reaction.
E)The reaction will require the input of energy to drive the creation of products.
2
How do catalysts affect the rate of a reaction?
A)They slow down the reactions because every reactant has to first join with a catalyst before products are created.
B)They have no effect on reaction rate because without them, the reaction would never occur anyway.
C)They increase the rate of reaction because they lower the activation energy.
D)They slow down the reactions due to the loss of free energy.
E)They increase the rate of the reaction by increasing the reactants free energy.
3
Which of the following statements is true about enzymes?
A)They are composed of carbohydrates.
B)There are very few different enzymes but each can catalyze many different reactions.
C)Enzyme catalyzed reactions are the minority in biological systems because, under biological conditions, most chemical reactions are spontaneous.
D)There are many different enzymes known, each catalyzing one or more specific chemical reactions.
E)Cells use enzymes to increase activation energies.
4
Most enzymes are globular proteins with one or more active sites where specific substrates can bind, forming a(n)
A)Enzyme-substrate complex.
B)Catalyst.
C)Product.
D)High-energy intermediate.
E)Stable intermediate.
5
Which of the following is not a factor affecting enzyme activity?
A)Temperature
B)Concentration of reactants
C)pH
D)Inhibitors and activators
E)Enzyme cofactors
6
The chief energy currency all cells use is a molecule called
A)DNA.
B)Enzyme.
C)Ribosome.
D)Activator.
E)ATP.
7
The total of all chemical reactions carried out by an organism is
A)Metabolism.
B)The reaction budget.
C)The reactant/product ratio.
D)Its energy budget.
E)Feedback inhibition.
8
How does the energy of sunlight enter into biological systems?
A)It decreases the kinetic energy of the molecules it contacts.
B)It oxidizes organic molecules in a redox reaction.
C)It facilitates the conversion of simple molecules into complex ones.
D)It breaks the bonds between carbon and hydrogen.
E)It is converted from potential to kinetic energy during photosynthesis.
9
Which of the following is the most comprehensive definition of "energy"?
A)The ability to make high-energy compounds.
B)The capacity to do work.
C)Changes in the amount of heat in a system.
D)Potential power.
E)Movement of molecules within a system.
10
Coenzymes differ from enzymes in that coenzymes are
A)active only outside the cell.
B)polymers of amino acids.
C)non-protein organic molecules.
D)higher in energy state.
E)specific for a single reaction.
11
Which of the following is MOST likely to affect the efficiency (activity) of an enzymatic reaction?
A)Changes in temperature
B)Changes in pH
C)Absence of cofactors such as metal ions in the active site
D)Presence of inhibitors
E)All of the above affect enzyme activity
12
How might a membrane improve the efficiency of an enzymatic pathway?
A)It creates order in what is otherwise a highly disordered cytoplasm.
B)It can orient active sites of enzymes in the same pathway towards a chamber containing the reactants.
C)It increases the amount of entropy in the reaction, giving the overall reaction a more negative (arrow)G value.
D)It decreases the activation energy of all the enzymatic catalysts by an equal amount.
E)None of the above are correct.
13
Which statement about thermodynamics is not true?
A)Free energy is given off in an exergonic reaction.
B)Free energy can be used to do work.
C)A spontaneous reaction is exergonic.
D)Free energy tends always to decrease.
E)Entropy tends always to decrease.
14
Which statement about enzymes is not true?
A)They act to speed up a biochemical reaction.
B)They are made up of RNA or protein.
C)They act to raise the activation energy of a reaction.
D)They are sensitive to heat.
E)They are sensitive to pH.
15
Which statement about feedback inhibition of enzymes is not true?
A)It is exerted through allosteric effects.
B)It is directed at the enzyme that catalyzes the first committed step in a branch of a pathway.
C)It affects the rate of reaction, not the concentration of enzyme.
D)It acts very slowly.
E)It is an example of negative feedback.
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